The present invention relates to fire extinguishers generally and more particularly to a simple spring loaded tubular fire extinguisher which can be either hand held and manually operated or equipped with a heat sensitive fuse link and mounted for automatic operation.
There are many different hand held fire extinguisher systems which can be used to manually extinguish a fire. Most manual extinguishers include either a dry or wet flame retardant chemical compound placed under pressure within a cylindrical canister which includes an opening in a bottom end, a siphon tube connected at one end to the opening and at an opposite end to a valve sealed outlet, an activation device for opening and closing the valve and a nozzle or a nozzle at the end of a hose which can be used to direct the compound toward a flame to extinguish the flame.
In operation, to extinguish a fire, a user directs the nozzle end of the hose toward the base of the fire and triggers the activation device to open the valve. Where the extinguisher includes a hose, the compound is forced therethrough and out the nozzle end to extinguish the fire. Usually, because the compound must travel through the hose prior to being discharged, hose length is limited so that activation time is reduced, pressure required to force the compound through the hose is minimal and minimal compound is wasted within the hose.
These types of extinguishers only work if pressure inside the canister is maintained at a high level. To ensure that pressure is sufficient, most of these types of extinguishers include, in addition to the hardware identified above, a pressure gauge fitted on the valve to visually indicate canister pressure. When canister pressure drops below a threshold level the canister must be recharged prior to use.
While these types of extinguishers are relatively inexpensive, unfortunately, they have a number of shortcomings. For example, while these extinguishers can put out relatively small fires efficiently, they are typically not suitable for extinguishing larger fires. These extinguishers require a user to be located relatively close to a fire in order to extinguish the fire. While a user can get close to a small fire without suffering heat related effects, large fires generate dangerous levels of heat which can scorch a person even though actual contact with the fire is avoided. It is particularly dangerous when an extinguisher is not equipped with an extension hose connected to the nozzle as a user must hold the nozzle adjacent a fire during extinguishment. Even when a hose is provided, as indicated above, to minimize activation time, reduce required canister pressure and minimize wasted compound, most extinguisher hoses are relatively short which means a user has to be near the fire during extinguishment.
Another problem with these types of extinguishers is that required components are expensive. For example, the pressure gauge is expensive. Another relatively expensive component is the canister which must maintain the compound under extreme pressure for extended periods. In addition to meeting pressure requirements under normal conditions, canisters must also meet varying pressure requirements which depend on ambient temperatures which can vary from below freezing to temperatures above 100.degree. F. Moreover, because many of the extinguisher chemical compounds are corrosive, the canisters have to be formed from materials which do not deteriorate when in contact with corrosive chemicals. All of these limitations require specifically constructed canisters which, due to their special construction are relatively expensive.
The task and related expense of providing a suitable canister is even more problematic when exotic canister shapes are desired. For example, space limitations might restrict the depth of a canister even though a space can accommodate a greater relative width. In this case, a canister having an oval or rectangular cross section might be most advantageous. Unfortunately, while such shapes are possible, they are usually cost prohibitive.
In addition, canisters which have to withstand high pressure tend to be heavy. Heavy metals which maintain their shape under pressure are typically used to form the canisters. For example, to provide a canister which can maintain ten pounds of extinguisher material under pressure for an extended period, extinguisher hardware will typically weigh as much as fifteen to twenty pounds for a total loaded canister weight of between twenty-five and thirty pounds.
Another related problem is that heavy extinguishers are difficult to operate. For example, where a large fire occurs or fire exists in a relatively high location (e.g., 6 or more feet above floor level), a user must lift an extinguisher up above the user's head in order to direct retardant compound at the fire. The task of lifting a heavy extinguisher is exacerbated by the necessity that extinguisher position must be relatively controlled so that compound is delivered in intended directions.
Moreover, the task of directing the extinguisher toward a fire is made more difficult by the reality that these extinguishers have to remain upright in order to operate properly. When upright, the retardant compound is located above the canister opening and the pressure causing gas is located thereabove as desired. When the valve is opened, the gas forces the compound out the opening.
Unfortunately, when the canister is not upright, the compound therein shifts under the force of gravity and will assume the lowest possible position inside the canister. For example, if the canister is upside down so that the opening is at the top of the canister, the compound will be opposite the opening. In this case, when the valve is opened the gas, not the compound, is discharged and the extinguisher is ineffective. This is also true where the canister is oriented longitudinally.
To overcome the weight limitations associated with these extinguishers, the pressure inside these extinguishers and the nozzle design are such that compound is discharged at extremely high speeds so that it can travel several feet relatively quickly. Unfortunately, a high pressure compound can often lead to "fire blast" and spreading. "Fire blast" is a term used herein to refer to the occurrence wherein fire can be spread from its original location when combustible materials thereat are blasted from their location. For example, where an extinguisher is used to extinguish a grease fire, the impact of high speed discharged compound can cause ignited grease to be splattered all over an adjacent area which, instead of extinguishing a fire, can spread the fire to the adjacent area.
Yet another problem with these extinguishers is that they have to be routinely maintained in order to remain operable. At the very least, pressure gauges have to be checked every few months to ensure canister pressure is above the required threshold level. Where canister pressure is insufficient, the canister has to be recharged prior to use.
One other problem with these extinguishers which is related to their having to be upright to operate properly is that they malfunction in zero gravity environments. For example, in outer space, where there is no gravity, even when oriented in an upright position with the canister opening at the bottom, because there is no gravitational force on the compound, the compound tends to float inside the canister, compound and gas inside the canister mix and, when the valve is opened, the mixture is discharged instead of pure compound.
In addition to hand held fire extinguishers there are also many different types of mounted fire extinguisher systems configured to automatically extinguish a fire. For example, there are water sprinkler systems which, when heat or smoke are sensed, deliver water through plumbing to one or more areas in a building to extinguish a perceived fire. While these systems are effective, they typically are the most expensive systems available as the plumbing hardware required can be extensive, particularly in large buildings.
Another example of a mounted extinguisher is described in U.S. Pat. No. 4,979,572 entitled FIRE EXTINGUISHER INSTALLATION which issued on Dec. 25, 1990 to the present inventor. That system includes a compact design wherein an extinguisher canister is secured by a two bolt bracket within a stove hood and is connected at an outlet end to a complex configuration of pipes, cables and one or more heat sensitive fuse links. The fuse links are located above the stove so that a fire on or near the stove will melt at least one link. When a link melts the cables cooperate with a trigger mechanism to open the outlet end of the canister. When opened the canister dispenses its contents (i.e. flame retardant compound) through the outlet and pipe configuration downwardly toward the stove to extinguish the fire.
This and other stove mounted systems are extremely important as a large majority of fires occur on or around a stove. By extinguishing stove fires rapidly most fire damage can be minimized and many fire related deaths and injuries can be avoided.
This system had many advantages over prior art stove top extinguishers including compact size, relatively unobtrusive appearance and ease of installation. Nevertheless, through use it has become apparent that this system has a number of shortcomings.
First, while requiring smaller and fewer components than the prior art, this system is still relatively complex and therefore expensive to manufacture. For example, this system requires at least two interconnected pipes for dispensing retardant material, several cable sections located outside the pipes and connected by fuse links, and a complex connection system for linking the canister to the pipes. In addition, the gas and electricity shut off mechanisms require many different mechanical components which are subject to breakdown.
Second, this system is still difficult to install. When installed the canister is located up and in a back portion of the hood. To install this system the bracket has to be fastened to a rear area of the hood's internal under surface. Where the hood is deep enough to facilitate installation access, to the hood's rear area is difficult. In addition, because the canister outlet must be at a specific angle and location with respect to the pipe system, the bracket must be adjustable and must be adjusted through trial and error during installation.
Third, once installed, this system may not have an appealing appearance. For example, where the internal portion of the hood is not sufficiently deep, the pipe and cable configuration might be readily observable below the front portion of the hood. In addition, the canister may be observable. This is particularly true where the hood is not deep enough to accommodate both the bracket and the canister.
Fourth, this system has some operational constraints. For example, the fuse links and cable sections are generally unprotected and could accidentally break dispensing canister material.
Fifth, after a fuse link breaks, the entire cable and fuse link assembly must be replaced in order to reset the trigger mechanism.
Sixth, part of the trigger mechanism is located outside a protective housing (e.g., pipe or other rigid housing). In this case, if the system is installed in a small area the moving trigger mechanism could be placed adjacent a hood section which might hinder triggering action thus rendering the system ineffective when the link breaks.
Seventh, these systems have many of the shortcomings that are described above in relation to the hand held extinguishers. For example, the high pressure canisters and gauges for these systems are typically expensive. In addition, the canisters are usually heavy so that mounting hardware has to be extensive and these systems have to be routinely maintained.
Thus, it would be advantageous to have a hand held extinguisher which is light weight, relatively inexpensive to manufacture, has a small size and is suitable for use in extinguishing large and small fires. In addition, it would be advantageous to have a mounted and automatic system which is also light weight, inexpensive, small and overcomes the other limitations associated with mounted systems above.